Caesar Cipher Encoder
What is Caesar Cipher Encoder
The Caesar cipher is one of the oldest known ciphers: each letter is shifted a fixed number of places down the alphabet. This encoder lets you pick any shift from 0 to 25 and turns your text into the classic rotated cipher, with ROT13 being just a shift of 13. Letters keep their case and everything else (numbers, spaces, punctuation) stays as it is. It all runs in your browser.
How to use
- Type or paste the text you want to encode.
- Drag the shift slider to the key you want, from 0 to 25.
- Read the encoded Caesar cipher in the output box.
- Copy the result or share the link with the text and shift already filled in.
When to use it
Want to set a quick puzzle or hide a spoiler in plain sight? Type your message, slide the shift to 3, and 'Hello' becomes 'Khoor'. It is a classic for classroom exercises, escape-room clues, and CTF warm-ups. To read it back, send the cipher to the Caesar cipher decoder, which can also try all 25 shifts at once when the key is unknown.
Frequently asked questions
What is a Caesar cipher shift?
The shift is how many positions each letter moves down the alphabet. A shift of 3 turns A into D, B into E, and so on. A shift of 13 is the well-known ROT13.
Does it change numbers or punctuation?
No. Only the 26 English letters are shifted. Digits, spaces, accents, and symbols pass through unchanged, and each letter keeps its upper or lower case.
Is the Caesar cipher secure?
Not at all. With only 25 possible keys it takes seconds to break, which is exactly why it is popular for puzzles and teaching rather than real protection. For real encryption, use the AES text encryption tool.
Can I share this with my text and shift pre-filled?
Yes. The URL updates automatically as you type. Copy it from the address bar or use the Copy link button, and anyone who opens it sees your exact text and shift ready to go.
Related tools
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